Hydrazonide titanium derivatives: Synthesis, characterization and catalytic activity in olefin polymerization. Molecular structure of [Ti(η5-C5H4SiMe3)Cl(μ-N2CPh2)]2

Reaction of the mixed dicyclopentadienyl titanium compound Ti(η5-C5Me5)(C5H5)Cl2 with LiN(H)NCPh2, in toluene at −78 °C, gives the hydrazonide(1−) derivatives (‘metalloazine’) Ti(η5-C5Me5)(C5H5)Cl[N(H)NCPh2] and Ti(η5-C5Me5)(C5H5)[N(H)NCPh2]2 in high yield. The titanium trichloro compound Ti[η5-C5H4(SiMe2Cl)]Cl3 reacts with hydrazone [H2NNCPh2] in the presence of one equivalent of NEt3 to afford the hydrazonide(1−) compound Ti[η5-C5H4(SiMe2Cl)]Cl2[N(H)NCPh2)], while in the presence of two equivalents of NEt3 the cyclopentadienyl-amido derivative Ti[η5-C5H4(SiMe2η1-NNCPh2)]Cl2 is obtained. Mono-hydrazonide(1−) compounds Ti(CpR)Cl2[N(H)NCPh2)] [CpR=η5-C5Me5, η5-C5H4(SiMe3)] were synthesized by treatment of the corresponding monocyclopentadienyl trichloro derivatives Ti(CpR)Cl3 with hydrazone in the presence of one equivalent of NEt3. The dinuclear complex [Ti(η5-C5H4SiMe3)Cl(μ-N2CPh2)]2 has been prepared by reaction of Ti(η5-C5H4SiMe3)Cl2[N(H)NCPh2)] with NEt3 in toluene and alternatively by reaction of Ti(η5-C5H4SiMe3)Cl3 with hydrazone and two equivalents of NEt3. The molecular structure of [Ti(η5-C5H4SiMe3)Cl(μ-N2CPh2)]2 was determined by single-crystal X-ray diffraction methods and contains two [Ti(η5-C5H4SiMe3)Cl] units bridged by two hydrazonide(2−) ligands which form a symmetrical ‘Ti2(NN)2’ core. These hydrazonide compounds have been activated with MAO and are suited to olefin polymerization.